Geometric isomerism is a type of stereoisomerism where compounds have the same molecular formula but differ in the spatial arrangement of their atoms. This phenomenon often occurs in alkenes and cyclic compounds, where restricted rotation around a double bond or ring structure leads to distinct isomers. The two main types of geometric isomers are cis and trans isomers, which differ in the positioning of substituents around the double bond or ring. In cis isomers, similar groups are on the same side, while in trans isomers, they are on opposite sides. This difference in arrangement can significantly affect the physical and chemical properties of the compounds, such as boiling points and solubility. Understanding geometric isomerism is essential in fields like organic chemistry and pharmaceuticals, where the activity of a compound can depend on its specific isomer.